I don't understand how "taking it slow" includes spending the night 3 or 4 times a week.
And how does "nothing serious right now" include spending the night 3 or 4 times a week?
It's our option to say "no" to spending the night. If we were to do that more often, maybe men would be more willing to commit.
There's much to the adage: "why buy the cow when the milk is free?" We often put the "cart before the horse" which allows him to "have his cake and eat it too"
Perhaps we should keep the milk refrigerated until we see how the relationship is going to go.
Shorty, I have heard that same statement from women so many times over the years that I have come to the conclusion that men must have joined the same club and their motto is: " I want to take it slow and see how it goes from here".
Tell him your plans enclude marriage at the end of "your" journey and see what happens. If he runs like a scared rabbit you have your answer. If you don't know very much about him or friends that know him well, find out, you may be the one running instead.
Like others said, he is not ready to commit and he shouldn't be forced to. Six months doesn't seem very long.
When something starts out firmly and then peters in the middle, it suggests he is losing interest or the intensity has been ramped up more than he has decided he likes.
6 months for a man is a long time. he should know by now how the relationship is going. i cant tell you to run or stay, but you should sit down with him and simply ask him.